1. Technical Field
The present invention relates to computer system maintenance. More specifically, it relates to a method for maintaining writes to vital product data (VPD) of field replaceable units (FRUs) in a computer system, and recovering failed writes to the FRUs.
2. Background Information
A computer system is composed of many FRUs, namely, circuit boards or parts that can be easily removed from the computer system and replaced, even by someone lacking in-depth product knowledge of the computer system. These FRUs include power supply units, motherboards, socketed microprocessors, primary storage modules (e.g. Radom Access Memories, or RAMs), secondary storage devices (e.g. hard drives and optical drives), video cards, sound cards, and peripherals such as keyboards, mice and printers. Replacing a FRU while the machine is running is known as hot swapping.
Many FRUs have VPD stored thereon that is vital to the setup or configuration of the computer system. The VPD is a collection of configuration and informational data associated with a particular set of hardware (e.g. a FRU), to allow for the set of hardware to be administered at a system or network level. The VPDs are used by a computer system to determine the nature of a specific hardware, and to shield the operation of the computer system from minor changes and variations of hardware implementations. VPDs may include product model numbers, unique serial numbers, product release levels, maintenance levels, and other information specific to the hardware, as well as user-defined information, such as the building and department location of the hardware. Some of the VPDs are updated periodically. For example, statistics such as power-on time or redundant memory bit steering information.
FRUs exist throughout the computer system, and are sometimes connected in series. Therefore, multiple FRUs usually lie intermediately in the path to access the VPD stored on a destination EEPROM (Electrically Erasable Programmable Read-Only Memory) on one FRU. As such, any problem in any one of the intermediate FRUs can lead to the problem of updating the destination EEPROM, even though the FRU containing the destination EEPROM remains functional. One solution to this problem is to treat any write failure to the destination EEPROM as a failure of the EEPROM, and to disallow any future reads from or writes to the EEPROM. Other solutions include providing alternate paths to the destination EEPROM.